Among the Diapriinae the Diapriini is the only tribe that includes truely symphilic species, some of them remarkably adapted morphologically to life with ants; these adaptations include extensive mimicry of the host ants which may include convergences in sculpture, pilosity, color behavior, and biology. Members of the genus Szelenyiopria share no specialized structures known from other myrmecophilic diapriini; but there is evidence of setae with truncate apices which were considered by Masner and García (2002) to be specialized structures, possibly as outlets for chemical substances ( Fig. 2 a
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).

Parasitized larvae of A. lobicornis were easily recognized by the dark coloration of the cuticle caused by the developing wasps ( Fig. 1
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b). All parasitized larvae belong to the reproductive forms of the ants, which can be recognized by the peculiar “ancoriforme” pilosity ( Fig. 2
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b) (Covello de Zolessi and González 1974). In this study, we verified that S. pampeana attacks both nests of A. lobicornis in two locations of La Pampa province; all recovered wasps were females ( Fig. 1
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e), and solitary parasitism was predominant. From the 33 ant larvae parasitized at La Reforma, 26 showed solitary parasitism ( Fig. 1
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c) and five larvae were gregariously parasitized with up to three diapriids per larva ( Fig. 1
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a, b). These results are not similar that those of Loiácono et al. 2000 for S. pampeana: the authors recovered in some cases, both sexes from a single host. Further, the number of wasps per larva ranged from 1 to 22; gregarism was predominant and the coexistence of two diapriid species of different genera was found ( S. pampeana and Trichopria formicans Loiácono). Loiácono et al. (2000) colected 1560 wasps (adults and inmatures) from 430 parasitized larvae from three partial colonies of A. lobicornis, which shows how aggressive these wasps can be in attacking the ants. Fernández-Marín et al (2006) suggest that these minute wasps present excellent opportunities to explore the hypothesis that parasitoid wasps regulate host population density and community structure both through indirect and direct effects.